Effect of Various Edge Conditions on Free-Vibration Characteristics of Isotropic Square and Rectangular Plates

In this chapter, vibrations of isotropic rectangular plates have been analyzed by applying the wave propagation approach. The plate problem has been expressed in integral form by considering the strain and kinetic energies. The Hamilton’s principle has been applied to transform the integral form into the partial differential equation of second order. The classical method namely product method has been used to separate independent variables. The partial differential equation has converted into the ordinary differential equations. The axial wave numbers are associated with particular boundary conditions. This is an approximate technique, which is based on eigenvalues of characteristic beam functions. The natural frequencies of plates are investigated versus modal numbers by varying the length and width of the plates with simply supported-simply supported (SS-SS), clamped-clamped (CC-CC), and simply supported-clamped (SS-CC) boundary conditions. The frequencies of the plates increase by increasing the modal number, and CC-CC frequencies are greater than the frequencies of other boundary conditions. Computational computer software MATLAB is engaged to characterize the frequencies. The results are compared with the earlier simulation work in order to test the accuracy and efficiency of the present method

Vibration Characteristics of Single-Walled Carbon Nanotubes Based on Nonlocal Elasticity Theory Using Wave Propagation Approach (WPA) Including Chirality

This chapter deals with the vibrational properties of single-walled carbon nanotubes (SWCNTs), based on nonlocalized theory of elasticity (NLT). The nanotube pilot control with nonlinear parameters was derived from Euler’s beam theory. The wave propagation (WPA) approach was used to derive the frequency equation describing the natural frequencies of vibration in SWCNTs. Complex exponentials depend on the boundary conditions given at the edges of the carbon nanotubes used. Vibration frequency spectra were obtained and evaluated for different physical parameters such as diameter ratio for single chiral carbon nanotubes and flexural strength for chiral SWCNT. The results show that the natural frequencies are significantly reduced by increasing the nonlocal parameters, but by increasing the ratio of the diameter length (aspect ratio), the natural frequency increases. The frequency of SWCNTs is calculated with the help of MATLAB computer software. These results are compared to previously known numerical simulations

Relationship between Awareness and Use of Digital Information Resources among University Students of Southern Punjab

The purpose of this study was to determine the relationship between awareness and use of digital information resources among students of universities in South Punjab. The researcher adopted survey research design and employed questionnaire as a research method to collect the data from respondents. The population of the study consisted on BS, Master, MS, M. Phil and PhD programs students of The Islamia University Bahawalpur and Bahauddin Zakariya University Multan. A convenience sampling technique was used to collect data from respondents. A statistical package for social science (SPSS-20) was used for the analysis of data. The result of the study found that majority of respondents used university library on occasionally basis and most of respondents give preference to digital information resources over printed materials. Most of the respondents agreed that they consult digital information resources for academic work, assignments and for the use of research purposes. Majority of the respondents had skills to used different database like HEC digital library, HEC Summon, Science Direct, JStore etc. A statistically it was found a strong relationship between awareness and use of digital information resources. The barriers faced by respondents while using digital information resources were; slow internet connectivity, respondents’ low ICT skills and limited access to university information resources etc

Vibrational Behavior of Single-Walled Carbon Nanotubes Based on Donnell Shell Theory Using Wave Propagation Approach

This chapter is concerned with the vibration analysis of single-walled carbon nanotubes (SWCNTs). This analysis is based on the Donnell thin shell theory. The wave propagation approach in standard eigenvalue form has been employed in order to derive the characteristic frequency equation describing the natural frequencies of vibration in SWCNTs. The axial modal dependence is measured by the complex exponential functions implicating the axial modal numbers. Vibration frequency spectra are gained and evaluated for physical parameter like length-to-diameter ratios. The dimensionless frequency is also investigated in armchair and zigzag SWCNTs with in-plane rigidity and mass density per unit lateral area for armchair and zigzag SWCNTs. These frequencies of the SWCNTs are computed with the aid of the computer software MATLAB. These results are compared with those obtained using molecular dynamics (MD) simulation and the results are somewhat in agreement

New α-Glucosidase inhibitors from Croton bonplandianum Croton bonplandianum Baill (Euphorbiaceae)

Purpose: To isolate and evaluate α-glucosidase inhibitors from dichloromethane extract of Croton bonplandianum Baill as probable remedy for management of diabetes.Methods: Activity-guided isolation of constituents from dichloromethane extract was carried out. Fractionation of dichloromethane extract by column chromatography on silica gel and Sephadex LH 20 using different mobile phase systems led to the isolation of compounds (A-I). The structures of these isolated compounds were established by ultraviolet (UV) and infrared (IR) spectroscopy. Proton nuclear magnetic resonance (1H NMR), 13C NMR and mass spectrophotometry, electron impact mass spectroscopy (EIMS) and high resolution mass spectroscopy (HRMS) were used for structural elucidation. All the isolated compounds were screened for their α-glucosidase inhibitory activity using standard in vitro α-glucosidase inhibition assay. Acarbose was used as positive control.Results: On the basis of their physical and spectral data from literature, the isolated compounds were identified as n-pentacosanyl-n-nonadeca-7′-en-9′-α-ol 1′-oate (A), n-tridecanyl n-octadec-9,12-dienoate (B), nonacosyl hexadecanoate (C), heptacosanoic acid (D), 1,3,5-trihydroxy-2-hexadecanoylamino- (6e,9e) heptacosdiene (E),cumarin (F), betulin (G), stigmasterol (H), and 3,5-dimethoxy 4-hydroxy cinnamic acid (I).Compounds F, GandI possessed significant α glucosidase inhibitory activity in a concentration-dependent manner with 50 % inhibitory concentration (IC50) values ranging from 23.0 to 26.7 μg/mL, relative to that of the positive control, acarbose (IC50, 38.2 μg/mL).Conclusion: The plant contains bioactive compounds with α-glucosidase inhibitory activity. This lendssome support for the traditional use of this herb in the management of diabetes. Compound F, GandI possessed significant α glucosidase inhibitory activity in a concentration-dependent manner and may be developed as a new α-glucosidase inhibitor.Keywords: α-Glucosidase, Inhibition, Diabetes, Acarbose, Cumarin, Betulin, 3,5 Dimethoxy 4-hydroxy cinnamic acid, Croton bonplandianu

Vibration Characteristics of Fluid-Filled Functionally Graded Cylindrical Material with Ring Supports

Vibration analysis of fluid-filled functionally graded material (FGM) cylindrical shells (CSs) is investigated with ring supports. The shell problem is formulated by deriving strain and kinetic energies of a vibrating cylindrical shell (CS). The method of variations of Hamiltonian principle is utilized to change the shell integral problem into the differential equation (DE) expression. Three differential equations (DE) in three unknown for displacement functions form a system of partial differential equations (PDEs). The shells are restricted along the thickness direction by ring supports. The polynomial functions describe the influence of the ring supports and have the degree equal to the number of ring supports. Fluid loaded terms (FLT) are affixed with the shell motion equations. The acoustic wave equation states the fluid pressure designated by the Bessel functions of first kind. Axial modal deformation functions are specified by characteristic beam functions which meet end conditions imposed on two ends of the shell. The Galerkin method is employed to get the shell frequency equation. Natural frequency of FGM cylindrical shell is investigated by placing the ring support at different position with fluid for a number of physical parameters. For validity and accuracy, results are obtained and compared with the data in open literature. A good agreement is achieved between two sets of numerical results

5-[(E)-(2,6-Dichloro­benzyl­idene)amino]-2-hy­droxy­benzoic acid

There are two geometrically different mol­ecules in the asymmetric unit of the title compound, C14H9Cl2NO3. The 5-amino-2-hy­droxy­benzoic acid units [r.m.s. deviations of 0.0323 and 0.0414 Å] and 2,6-dichloro­benzaldehyde groups [r.m.s. deviations of 0.0285 and 0.0226 Å] are roughly planar and oriented at dihedral angles of 11.69 (13) and 83.12 (6)° in the two mol­ecules. An intra­molecular O—H⋯O hydrogen bond completes an S(6) ring motif in each mol­ecule. The two mol­ecules form dimers with each other through inter­molecular O—H⋯N and C—H⋯O hydrogen bonds, completing an R 2 2(8) ring motif. The dimers are inter­linked via inter­molecular O—H⋯N and C—H⋯O hydrogen bonds, forming polymeric sheets

Improvement of Strength and Permeability Attributes of Silty Sand Type of Soils using Enzyme Induced Calcite Precipitation

ABSTRACT Enzyme Induced Calcite Precipitation (EICP) is one of the soil stabilization techniques based on microbiological activity. In this technique, urea decomposes with the aid of urease enzymes in the presence of calcium chloride and produces calcite, which acts as a bio-clogging and bio-cementing material. In this study, test tube experiments are performed to assess the optimal amount of calcium chloride, urea, and urease enzymes to be used for engineering applications. The silty sand type of soil is treated with different proportions namely; P1 (0.1g urease enzymes, 0.375g urea, 0.9g CaCl2), P2 (0.2g urease enzymes, 0.75g urea, 1.8g CaCl2), and P3 (0.4g urease enzymes, 1.5g urea, 3.6g CaCl2), to analyze their effect on strength and permeability attributes of soils after 14 days of curing time. It was observed that an increase in EICP content causes a substantial increase in shear strength particularly cohesion due to the bio-clogging phenomenon induced in soil particles by EICP which eventually leads to a decrease in permeability and inhibits the activity of urease. Overall, P3 yields higher cohesion (48 kPa) than P1(40 kPa), P2 (43kPa), and untreated soil samples (31 kPa). Furthermore, P3 causes a significant decrease in permeability as compared to P2, P1, and untreated soil samples tested after 14 days of the curing period. The findings of the study suggest the successful implementation of EICP for soil stabilization. Key Words: Enzyme Induced Calcite Precipitation (EICP); permeability; shear strength; bio-clogging; bio-cementation

Landscape associations of Asiatic black bears in Kashmir Himalaya, Pakistan

The Asiatic black bear (Ursus thibetanus) is threatened throughout its range and assessed as nationally vulnerable in Pakistan. Habitat degradation and loss, illegal exploitation, and human-bear conflict are key threats to the species, but there is a lack of empirical knowledge regarding its occurrence in Pakistan. In 2012, we conducted a sign survey study to classify Asiatic black bear presence in a little studied and isolated region of the Kashmiri Mountains in Azad, Jammu and Kashmir, northern Pakistan. We compared bear presence in 5 habitat types (agriculture, forest, pasture, plantation, and scrubland) across an elevational range of 910 to 2, 990 m. We used hierarchical logistic regression analysis to identify whether elevation, habitat and/or the interaction between the two explained bear presence in the region. Type of bear sign was significantly associated with some habitats, although claw marks were not associated with any habitat type. The strongest positive predictor of bear presence was the interaction between elevation and forest habitat, with greater presence (37.5%) in forest habitat at higher elevations between 1, 890 and 2, 855 m. The predicted likelihood of bears occurring in agriculture, plantation, and scrubland habitats was always 30% in forest habitat. Our findings contribute to the national understanding of black bear presence and we provide recommendations for actions that support effective conservation management of the species in Pakistan